Complete LSJ Swap - Boost Forum

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Complete LSJ Swap
Thursday, September 20, 2012 6:43 PM
So PJ and others like Matt have or are working on complete LSJ motor swaps.

Here are a few things I know.

1-The motor will bolt right in, and bolt to a F23 with the use of the same spacer that is on the Cobalt SS.
2-The power steering will bolt to the same spot that it is on the L61.
3-A block off plate will need to me made for the Cam Sensor on the back of the head.
4-There will need to be modification to the waterpipes on the driver side of the motor to make the LSJ oil cooler work.
5-Would need the trigger wheel to make it all work.
6-Have to change oil pans.

Here are things I dont know.

1-Will the L61 waterpipes work WITHOUT the use of the LSJ oil cooler?
2-What combination of flywheel/clutch/pressure plate will be needed?
3-Are there any sensors or senders on the LSJ that we do not need for Jbodies?
4-Are there any sensors or senders the Jbody ECM needs but the LSJ doesnt use?

Here is some stuff from PJ back in 2008ish just for me to read.

DaFlyinSkwir(LS61) /PJ/ OEM+ wrote:

seeing as I've taken countless L61s apart, and tore down an LSJ to practically nothing, and I have an LS61 (L61 head+ LSJ block) in my car at the moment, allow me to elaborate (much like airtonics did)


1.) take an LSJ engine (oil pan, block, head, header, intake monifold, s/c) from the junkyard,

thats fine. They can usually be had for $2500 out of a junkyard for a complete engine (including s/c and harness)


2.) installed the L61 valve cover (since the the bolts for the middle cover, or CDI in the L61, are different), so one can put on the L61 CDI,

Can't put the L61 valve cover on the LSJ, the LSJ has two flanges on the backside of the engine (driver side if you think sideways FWD style) and the L61 valve cover only has one bump (where the power steering mounts).

L61 head:

LSJ head:

you can only use the appropriate valve cover (cam cover, whatever you wanna call it) with the matching head.
The ignition systems will also only bolt onto their matching valve cover. I'll double check this tonight since I have both an L61 ignition and LSJ ignition sitting at home.

The LSJ also uses different style spark plugs than the L61. I'm pretty sure the cobalts have a small washer to seal, while the L61 has a taper seat.

Another risk is that the flange for the cam sensor on the LSJ (the one closest to the firewall, or to the left in the picture above) has a possibility of running into the brake booster of the Jbody. Since nobody has tried that yet, its still not really known whether or not it would physically fit.


3.) connect the L61 harness to the sensors on the LSJ block,

several problems here.
first, the LSJ moves some sensors around. The coolant temperature sensor being the biggie. The L61 has its sensor on the back by the thermostat housing. The LSJ has it in the head near the upper coolant hose. You'd have to cut and extend the wire to way up there, but this also leads to another problem...

the LSJ has an oil cooler, which gets in the way of the L61 thermostat housing. The LSJ's thermostat housing interferes A LOT with the F23 transmission.

You can either make a bypass hose for the cooler by threading into the sleeves in the oil filter boss, or some other way. YOU CANNOT just block them off, because the cooler is situated so that oil is forced to go through it. Blocking both holes off will cut off oil recirculation, and starve the engine of oil. If you bypass the cooler, you can use the L61 thermostat housing no problem, as well as the L61 lower radiator hose.

The problem with this is I'd want to keep the cooler since you want the supercharger, AND the LSJ has piston squirters and while I'm no genius engineer, I'd imagine they absorb quite a bit of heat from the underside of the pistons (why they're there) so the cooler probably helps keep the oil from getting heated, and keeps the engine and oil healthy.

If you do keep the cooler, you have to re-arrange your coolant hoses because you now have 2 extra connections for the oil cooler (its plumbed with coolant to cool the oil.. yes an oil to water cooler)

secondly, no one (including myself) knows quite how the LSJ will interact with the F23 transmission yet. The LSJ has an 8 bolt flywheel and a larger diameter clutch. The O.D. is the same so it fits inside the bellhousing no problem, but the depth of the clutch is different, and the bolt patterns are VERY different from L61 clutches so its impossible to make a hybrid of the two, you have to use either one or the other (I'm using a stock cobalt SS clutch with my F23 transmission, and a cavalier clutch actuator.. still HOPING it works but I haven't finished the project just yet)


4.) maintain the (in my case) automatic transmission from the L61 and bolt it on to the LSJ (I'm not sure on the bolt pattern, though, but I am pretty sure they would be the same since it is the same basic block),

The bolt pattern is indeed the same, but getting a flex plate and a torque converter for the LSJ might be hard since they were never offered with an automatic transmission. Custom units could be ordered I suppose. IDK if the thermostat housing will interfere with the auto or not.


5.) install an aftermarket fuel pump (or maybe even the LSJ fuel pump),

I would leave the LSJ fuel pump alone. Racetronix is the best in-tank fuel pump upgrade for the jbody at the time (unless you go insane)


6.) take the resovoir, aftercooler and pump from the LSJ and adapted it to the Cavalier like bolting on an intercooler,



7.) if the lower mount and/or oil pan is different then excahnge the LSJ with L61 oil pan and lower bracket,

L61 pan has to go onto the LSJ block.

You also need to use the L61 upper engine mount, the cast aluminum peice that bolts to the block just above the timing chain access cover (the LSJ's cast engine mount is different) as well as the L61 alternator, and belt tensioner.


8.) and take the Cavalier to a GM dealer and have them reprogram the PCM for the GM Cavlaier/Sunfire Supercharger Kit #17800003 (although that reprogram is for 8 psi or boost not the LSJ 12 psi, maybe slip the tech a 20 to boost up the fuel table).

this is your major oversight. The L61 has a 6+1 reluctor ring that is CAST onto the crankshaft. This tells the crankshaft position sensor where it is, and gives it a reference for the ignition system (as well as the fuel injection system)

the LSJ on the other hand, has a 60-2 reluctor ring thats bolted on. Getting to it however, requires disassembly of the block and removal of the crankshaft.

you can use a trigger wheel and feed the sensor signal to the jbody pcm and get the reflash.
or, you could have a custom trigger wheel made and bolt it into the LSJ (again you have to COMPLETELY DISASSEMBLE the bottom end to get to it.
or, you can run a megasquirt or other stand alone computer system. the jbody ecu is not something you really want to retain.. like, ever.

quick breakdown:

L61 (2.2 n/a)
86mm bore 94.6mm stroke
cast crank, 1015 steel rods, cast pistons (dish)
10:1 compression ratio

lost foam cast head
one cam flange

7 tooth trigger wheel (6+1)
6 bolt flywheel
5 rib serpentine belt

wasted spark coils on plug (twin coils)
"compression sense" cam source generator

LSJ (2.0 s/c)
86mm bore 86mm stroke
forged steel crank, 5115 steel rods, cast Mahle pistons (donut dish)
9.5:1 compression

sand cast head
two cam flanges

58 tooth trigger wheel (60-2)
8 bolt flywheel
6 rib serpentine belt (reverse spun alternator)

true coil on plug ignition (four coils)
cam sensor spun by exhaust cam

note: you CANNOT mix and match rotating assembly components (crank, rods, pistons) they have to be a matching set. However, it is possible to use a L61 rotating assembly in an LSJ block, or an LSJ assembly in an L61 block.

with all that said, here's my advice:

an LSJ/L61 hybrid isn't for the faint of heart (or someone with money or wife problems). If anything, buy a fresh L61 out of the junkyard (much lower mileage) and bolt the s/c kit onto it and be done. The amount of work you're looking at doing is NOT for someone who isn't prepared to throw a lot of cash at their car.

Edited 1 time(s). Last edited Thursday, September 20, 2012 6:47 PM

Re: Complete LSJ Swap
Thursday, September 20, 2012 10:25 PM
EvoFire wrote:

Here are things I dont know.

1-Will the L61 waterpipes work WITHOUT the use of the LSJ oil cooler?
2-What combination of flywheel/clutch/pressure plate will be needed?
3-Are there any sensors or senders on the LSJ that we do not need for Jbodies?
4-Are there any sensors or senders the Jbody ECM needs but the LSJ doesnt use?

1- Yes, but you will need to address oil passages left open from removing the cooler. The adapter PJ has with a looped line is the easiest delete IMO, or you could do like Newt on his LE5 bottom and tap the holes, one he used for a gauge and the other I forget. You cannot on the other hand just run a block off plate or understanding is by simply blocking the passages it'll create pressure loss
BUT back to the answer, if you delete the cooler, the l61 thermo housing and pipe fits just fine. I believe that is what PJ is currently running.

2- you need to run the LSJ clutch/flywheel/pressure plate...the LSJ is a 8 bolt flywheel. Everything past that is all f23...keep your throw out bearing, clutch pipe, etc. I got low mileage stock clutch/flywheel off CSS for like $70 shipped

3- they have a cam sensor which we don't use (hence the block off plate), and I'm no sure about the lsj, but my lk9 had a sensor in the bottom of the oil pan (which doesn't really matter since it gets swapped)

4- it's pretty much all plug and play. Oil pressure sensor is on the filter housing on the lsj, so you may need to extend wiring a bit, as well as extending the ckp wiring to reach the trigger wheel. All connectors on any motor sensor are the same though, so everything will plug right in. Oh, and the coolant temp sensor is in the head next to the little coolant overflow line, so which thermo housing you use will determing if you use it. If you're running the l61 housing, the coolant temp sensor would obviously stay where it's at and you can ignore the one in the head. If you're modding a lk9/lsj thermo housing to fit, they lack a sensor so you would use the one in the head.

Oh, and youll need to address some interference at your brake master cylinder. The front hard line rubs on the exhaust cam sensor casting. 2 options - Newt just ground a little meat off the casting and block off plate for clearance (and there is plenty of metal there to remove from), or I chose to just massage my brake line a bit to make it fit (il be switching to braided line soon and my 90s clear so i wasn't to concerned with modding the head)

I also believe you need to modify your coil packs to fit the cam cover, and the plate on top needs modifying to fit the ignition module. I'm running msd coils and wires so I wouldn't know what exactly needs done, but I'm sure pj can answer that.

I'll post pics in my thread that you asked for when I'm home, regarding using the l61 water pipes with the oil cooler

It's really not as overwhelming as it sounds on paper, lol...once you get the motor in front of you and compare it to the what's in the car, you'll see exactly what needs to be done. And since PJ is willing to make some more ckp brackets that puts a big chunk of the "modified" part to rest, and I made a few extra cam block offs while I was at it if you need one.

Edited 1 time(s). Last edited Thursday, September 20, 2012 10:32 PM

Re: Complete LSJ Swap
Thursday, September 20, 2012 10:47 PM
Thanks Matt. I already run the LSJ valve cover, so i have the ICM stuff and cover plate already made and on my car.

are the Tstats the same?

Edited 1 time(s). Last edited Thursday, September 20, 2012 11:19 PM

Re: Complete LSJ Swap
Friday, September 21, 2012 1:22 AM
To my knowledge the thermostats on all eco's are the same...just the housings that differ.

Re: Complete LSJ Swap
Friday, September 21, 2012 2:19 AM
for my oil cooler delete, what I did was I ordered an adapter from custom fabrication (they make stuff for ariel atoms) that allows you to run an externally mounted cooler.

the stock LSJ oil cooler uses coolant to cool the oil. my adapter lets you run an bumper mounted air unit instead.

you cannot block off the holes because ALL the oil the engine pumps goes through this section at some point (the filter housing).
you can block it off if you remove the sleeve that is present in the rear-most hole (closest to the block).

when you use the delete that I have, you can use the stock L61 thermo housing and coolant pipe.

the only sensor issue is like matt said, you get an extra coolant temp sensor on the head by the upper rad pipe. convenient if you plan on running megasquirt at some point (cough)me(cough)

there's a lot of little things to do, but overall this swap, for the most part, is plug and play. the only iffy thing is the crank sensor relocation and stuff, but the bracket that I made (plus phil's trigger ring) makes that kind of a simple thing to do now.

Re: Complete LSJ Swap
Friday, September 21, 2012 3:03 AM
when did my swap. i removed the metal sleeve and made a block off plate out of aluminum. I was going to drill and tap the wholes like Newt. i just didnt have bits and taps large enough. I have zero issues and lots of oil pressure. Also running L61 waterpipe/ thermo housing. no issues again. everything was complete bolt on the same as a factory L61. timing the trigger wheel was a pita at first but i think i got it sorted out. Full mod list can be found in my profile.

Re: Complete LSJ Swap
Friday, September 21, 2012 5:54 AM
Matt- I want one of those cam block off plates, how much sir?

Hey PJ, maybe you could make a few more ICM mount plates for the cam cover, and let them go for a few bones to other LSJ swappers.... that are fab free (meaning have little access to machining, cutting, welding tools) hint, hint. Package deal with the crank sensor plate setup?

I love the idea of using the Custom Fabrications plate to run an external cooler, it will be interesting fitting a cooler up front with the heat exchanger though.... may have to go to the drawing board on that one, its a shame we don't have enough room in the front to run a V mount like the drifter guys do in Nissans....

Re: Complete LSJ Swap
Friday, September 21, 2012 9:55 AM
matt gimme a price too....and PJ lets get the CPK mount going. i could maybe have this motor in my hands in a month or so.

Re: Complete LSJ Swap
Friday, September 21, 2012 1:56 PM
And for tuning, I am thinking that I could probably have the tuner pull a tune for a jbody off of HPT forums, and just start with that.

Re: Complete LSJ Swap
Friday, September 21, 2012 4:39 PM
And for Matt and PJ, what would you guys expect from a intercooled ported and polished m62 wiht a 2.9 or smaller pulley and 60's?

Re: Complete LSJ Swap
Friday, September 21, 2012 6:44 PM
EvoFire wrote:

And for Matt and PJ, what would you guys expect from a intercooled ported and polished m62 wiht a 2.9 or smaller pulley and 60's?

I think Kyle dyno'd around 240ish on a 2.9, 63's, dual pass/zzp s3 and stock redline. I think he'd be a bit above once Ryan pulled his rev limit out to 7k, and I remember jucnbst making about 250 with a 3.0 and all his supporting mods
That being said, a good tune on an LSJ, i think you'll pass 250 with much past will be dependent on the tune. Go 7k redline, and LSJ's love a little extra timing...I'd think a 2.9 has the potential to get 275+. I'd look at CSS and see what the delta guys are actually making on various pulley sizes.

Re: Complete LSJ Swap
Saturday, September 22, 2012 6:55 AM
Add meth with that tune and it'll allow you to get quite a bit of extra timing.

You'll be in the 260 range.
Re: Complete LSJ Swap
Saturday, September 22, 2012 7:22 AM
if it helps i was running a 2.8, blower cams, LS1 tb, 60s, ported head, full cooling mods, meth not working with zero knock, and super super rich and im 275 whp.

Re: Complete LSJ Swap
Monday, September 24, 2012 5:09 AM
That does help Alex^. I like that, I'm getting more and more excited for this swap.

Re: Complete LSJ Swap
Saturday, October 27, 2012 11:09 AM
I found an LSJ with the supercharger and the guy wont split the two, if I buy it, should I bother swaping just the supercharger parts to my L61 or should I just swap the whole thing over?
Re: Complete LSJ Swap
Saturday, October 27, 2012 11:32 AM
Up to you how much extra work you want. The LSJ swap isn't all that complicated, but its definitely not 100% bolt on like just throwing on the blower on an l61.
Tuning seems to be a bit more of a challenge with the whole swap. Not sure what Alex is running, but I'm on the LD9 harness/PCM with the speed density flash, car is up and running, but tuning is a bit of a stab in the dark (we're actually tuning as I type). We're finding ourselves changing alot of values in most tables (tuning with HPT) to compensate for the different motor, and the tune still isn't liking boost too much. Definitely more work on the tuning side I'd say, if you decide on the full on swap.

On the plus side, the lsj will take a bit more abuse then the stock l61

Re: Complete LSJ Swap
Wednesday, May 22, 2013 11:49 AM the other hybrid set ups, Id like to see this one stay up to date.
Ive got an opportunity to get a healthy 5,000 mile LE5 (and he'll throw in a full L61 for free) for $800.
If i can toss the 2.4 in and do the mods discussed in here (oil cooler, cam block off, crank sensor, etc) then I can have a motor able to handle anything my M62 can throw at it as well as get another L61 out if it to rebuild and sell for maybe cam upgrades or something (since my stage 2 L61 cams wont be of much use if i get an LSJ/LE5 motor).

Im guessing the Transmission will bolt right up to the LSJ/LE5 without any modifications except the adapter spacer or whatever right?

I like the idea of this LE5 having almost literally no's like a rebirth of the cavalier for years of abuse!...?

04 Cav. 2dr. 5spd. My DD. 'Nuff said.
Re: Complete LSJ Swap
Wednesday, May 22, 2013 12:54 PM
Derek, what year LE5? Gotta be careful, only the 06 and early 07 models had forged internals...later 07 and on they switched back to powdered steel is no stronger than the L61. And on another note, since you can't use the LE5 head, they're pretty easy to sell on CSS or some Solstice forums. I actually sold my complete LE5 head when I was going that route on Craigslist for like $200.

Your existing flywheel/clutch will bolt right up to the LE5 block, both the LE5 and L61 share a 6 bolt crank. You'll need to use an LE5 head gasket with it due to the larger bore size. I forget what Ryan (oldskool) roughly calculated the CR to be with an LE5 block, L61 head, and stock LE5 head gasket...might have been in the 11:1 range but I honestly can't remember. Regardless, itd equal fun with a blower strapped on it.

There is one area on the LE5 block you'll need to clearance...there is a aluminum brace that bolts to timing side of the block, that the upper motor mount bolts into (you'll need to use the brace from your L61), there is a little casting you need to grind off for fitment, sort of like when you grind the L61 head for the m62 tensioner. You'll see exactly what needs done when you hold the brace up to the block

Only thing I would keep in mind, is the LE5 is a bit less favorable rod stroke ratio for a blower, definitely not gonna be a high revver like and LSJ. But despite that, I still think a blown LE5/LSJ hybrid would make for a fun car.

Re: Complete LSJ Swap
Wednesday, May 22, 2013 2:04 PM
its a 2006.
and i didnt know the LE5 head wouldnt id still need to get a hold of an LSJ head...basically Id be giving myself a larger displacement with forged bottom end, so it'd be able to easily handle the M62 set up Id throw at it.
I know its not really a lot of work, it just sounds it. And Im not worried about having to shave a little off the block if necessary, as long as im not re-engineering the car lol.

There is a fully assembled LSJ for $500 on CSS...maybe thats a better route. Though that one would require a spacer adapter or soemthing for the housing right? the LSJ is an 8bolt? but it would mate up to the F23 perfectly with a single dealership part?

Im so torn... the LSJ is used, i think about 60-80k miles. The LE5 would be abit more money but practically brand new (no need for the $200 timing set Id do on the LSJ or L61 rebuild).

$800 LE5, use bottom, sell top, buy LSJ head, sell L61 cams, buy LSJ cams
$500 LSJ, more mileage but bolts in with little effort and without needing to sell anything if i went with stock cams (still sell my L61 cams)


04 Cav. 2dr. 5spd. My DD. 'Nuff said.
Re: Complete LSJ Swap
Wednesday, May 22, 2013 2:33 PM
Yeah the LE5 is no use to us...VVT , direct onjection..totally different beast.

I'd grab the LSJ for $500, sounds like the cheapest, most efficient way to get a running motor in your car sooner than later. If you go with the LE5 bottom, then you are still tracking down and buying an LSJ head to mate to it, you need a trigger wheel set up either way you go, I'd just toss in the LSJ and call it a day.
You'll need the transmission adapter plate from GM (it's like $30 or something), and you will need an LSJ clutch and flywheel (as they are 8 bolt cranks) will then bolt right up to the f23. Check in with Jeff Reiland (mongorat) on CSS, he gave me a great deal on the LSJ clutch and flywheel, and I'm sure he has more. I'm also told (not 100% sure) that the LNF clutch/flywheel is essentially the GMPP upgrade for the LSJ. Jeff usually has some of those as well.

So you if you go full LSJ, you're literally looking at just swapping oil pans, making a cam block off plate, setting up the trigger wheel/ckp, and doing whatever you are gonna do with the thermostat housing, whether it be use the adapter PJ uses, have the LSJ housing cut and welded to clear the shift cable bracket (like I am), or just T into your heater core lines and loop the oil cooler through them (using the l61 housing).
Quick easy swap, no changing heads like with LE5 bottom, basically a few quick mods, drop it in, and drive

Re: Complete LSJ Swap
Wednesday, May 22, 2013 4:05 PM
Yeah I was not aware the LE5 head didn't work..was just attracted to the even bigger displacement.
Ill talk to that guy on CSS and see if he's willing to ship for $500..only problem is I may still need to do the timing set since its not new..I guess while its out already right?
thanks for your help...I really just want a solid plan and get this done. but with the lack of low mileage L61's around, its easier to just do a slight upgrade and know Im going to be more solid this time around anyways. Basically anything I throw at it it'll handle.

Ill see whats up with it, if he's willing to do it still!

04 Cav. 2dr. 5spd. My DD. 'Nuff said.

Re: Complete LSJ Swap
Wednesday, May 22, 2013 4:15 PM
^^Dont bother with the timing set. Slap a new style tensioner in it right off the bat and im sure itll be good for ages.

That and maybe pull the timing cover off and make sure none of the guides are worn or broken. Pull out the upper guide cover and make sure that bolt is still in its spot. Only thing itll cost you to do all that is $50 for the tensioner and maybe $8 for the crank bolt.

Id slap the tensioner while the front cover is off so you can watch to make sure the chain doesnt move. But go with the LSJ if you feel confident in getting the timing ring in the right spot.

That being said we need someone to make a ring that bolts to the stock pulley and is setup perfect. I know MD knows the degrees now...
Re: Complete LSJ Swap
Wednesday, May 22, 2013 4:26 PM
well I just posted on his thread but noticed he may only be selling the block...and its been sitting for a few years in a garage. it has 52k miles which isn't bad...but unless he comes down or mentions everything from top to bottom is included, nvm...

basically whatever I end up getting, ill have on a stand and just inspect it really well at that point before dropping it in. what worries me is his has been sitting for years and who knows what condition its in, internally

04 Cav. 2dr. 5spd. My DD. 'Nuff said.
Re: Complete LSJ Swap
Wednesday, May 22, 2013 4:48 PM
If it makes you feel better I grabbed a eco from the wrecker a while back and it sat for atleast a couple years. I didn't do anything to it prior to storage. I bought a cav with a blown motor and put it in it. That was 3 years ago. My buddy now owns the car.

Im sure its better for it do have some oil or something in the cylinders. If it doesn't have a oil pan that kinda sucks....just cause its nice to have things sealed up.

I still am siding on grabbing a 100% stock L61 for the time being. Inspect it, add new style tensioner, tap head for the larger studs and drive it while building some cool hybrid.

For the time being anyways..
Re: Complete LSJ Swap
Wednesday, May 22, 2013 4:56 PM
that may be what I have to do...I want it back on the road and LSJs are not common in complete form here.
Ill keep looking around and see what comes up...

04 Cav. 2dr. 5spd. My DD. 'Nuff said.
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